Controlling means for elevators.



G. K. MITCHELL.

CONTROLLING MEANS FOR ELEVATORS.

APPLICATION FILED SEPTA. I914.

Patented Apr. 24, 1917.

V the drawing.

GUY K. MITCHELL, OF BALTIMORE, MARYLAND.

CONTROLLING MEANS FOR ELEVATORS.

Specification of Letters Patent.

Patented Apr. 2%, 1917.

Original application filed March 13, 1912, Serial No. 683,576. Divided and this application filed September 4, 1914. Serial No. 860,229.

To all whom it may concern:

Be it known that I, GUY K. MITCHELL, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Controlling Means for Elevators, of which the following is a specification.

This invention relates to hoists or elevators, and is particularly adapted for use in connection with electrically operated elevators. The present application is a division of my prior application, Serial No. 683.576, filed March 13, 1912.

The object of the invention is to provide improved means for automatically shutting off the power from the motor as the car approaches the limits of its movement, such means being designed especially to prevent over-throwing of the control wheel or device in machines where the car travels at comparatively high speed.

In order that my invention may be readily understood, reference is had to the accompanying drawing forming a part of this specification, and which shows a conventional or diagrammatic view of a control system for an elevator embodying my improvements.

Referring to the drawing, 2 designates the usual hand rope which passes over a control wheel 4: at one end and over an idler 3 at the other end of the shaft. The wheel 4 is fast on a shaft 5, which may actuate power controlling mechanism of any desired type. Ordinarily, as hereto-fore constructed, it has been common to provide knocker balls on the rope 2 so arranged as to be engaged by the car as it approaches the limits of its travel so as to automatically bring the wheel 4 back to neutral position and thus shut off the power.

Where the car operates at high speed, however, great difliculty has been found in practice on account of the overthrowing of such wheel past the stop position. It is with a view to overcoming this difliculty that I have provided the arrangement shown in Referring to the drawing, it will be seen that in addition to the usual hand rope 2, I provide an auxiliary control rope or cable 6 which passes at one end around an idler 7 and at the other end around a wheel 8. Secured to the wheel 8 is a small sprocket wheel 9 which is connected .by means of a chain 11, or other suitable gearing, to a larger sprocket wheel 10 rigidly connected with the shaft 5 or wheel 1. Knocker balls 13 and 14 are secured to the rope 6, and are adapted to be engaged by a projection 12 carried by the car 1.

By virtue of the reduced speed gearing between the wheel 8 and the wheel 4, it will be seen that the rope 6 will have a much greater travel than the rope 2. Suppose, for example, that the ratio between the wheels 9 and 10 is one to three. This would mean that after engaging the knocker ball the car could move say six feet without moving the control rope 2 more than two feet. In other words, by the employment of such reduction gearing, the car is given a much greater distance in which to come to rest after striking the knocker ball than would be possible where the knocker balls are mounted directly upon the manual control rope 2. Therefore, with my improved arrangement, it is no more diflicult to automatically stop a high speed car than it is to automatically stop a low speed car with the old arrangement. It will, of course, be understood that any desired form of speed reducing gearing whatever may be employed.

What I claim is:

1. In a power-operated hoist, a car, manually actuated means for controlling the supply of motive power to said car, and car actuated means for automatically operating such controlling means as the car approaches the limits of its movement, and speed reducing gearing permanently connecting said car actuated means with said manually actuated means, so that they always move together, but at difierent rates.

2. In a power-operated hoist, the combination with a car, of the usual hand rope for controlling the movement thereof, a wheel over which web. rope passes, a cable, a

second Wheel over which such cable passes, In testimony whereof I have aflixed my knocker balls secured to said cable in the signature, in presence of two Witnesses. path of a projection movable With said car, GUY K. MITCHELL. and reduction gearing permanently connect Witnesses:

5 ing said Wheels so that they always move NOEL L. BURNs,

together, but at different speeds. E. RUTH RICHARDS.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

